This invention relates to maintenance and service of complex systems and more specifically a relational database and structure thereof for maintenance information for use in maintenance of such systems.
Complex systems comprising tens or hundreds of inter-related and inter-operating systems and subsystems, many which may be complex in there own right, present unique maintenance and service challenges. Examples of such complex systems include factories, major buildings, ocean-going vessels, power generation plants, and aircraft to name a few. Complex systems and the inter-related and inter-operational nature of the systems and subsystems thereof often require equally complex and disciplined maintenance and service programs. These maintenance and service programs usually include documentation or records of observed or indicated irregularities or discrepancies and actions taken or services performed pursuant to resolution or prevention of such irregularities and discrepancies. This documentation is usually filled out, completed, or recorded by service and maintenance personnel. Expert systems and tools that can standardize service and maintenance documentation, diagnoses, procedures, cost estimates and so on are highly desirable for the time savings and precision they can offer to an overall maintenance and operational support program.
In the aircraft industry, for example, Fault Models have more recently been developed as a means to assist with maintenance of an aircraft. A Fault Model is a set of data items that represent the elements of a complex system, such as an aircraft, their failure modes, the symptoms produced by those failure modes and other information as required to allow an automated reasoning system to use the data to assist maintenance personnel in the maintenance and correction of operational discrepancies of the complex system. Fault Models have been successfully produced as a bi-product of the engineering development of a new system. For example, this was accomplished for the Boeing 777 Aircraft. The 777 Engineering Development process included significant additional controls to ensure that fault isolation data was captured in a structure that allowed the production of an accurate fault model. Development of earlier aircraft as well as the development of most other complex systems did not include a rigorous approach to the capture of fault isolation data. The 777 Fault model has significant limitations not the least of which is that it only works for 777 aircraft. A typical US airline will have several major fleets, such as a Boeing 757 and Airbus A320 fleets, and a dozen or more sub-fleets, such as 757-27A and 757-27B sub-fleets. In addition, the configuration of the aircraft changes over time to incorporate safety, reliability and passenger comfort improvements.
Furthermore the 777 Model offers little or no guidance with respect to fault isolation, does not handle updates to the equipment in an orderly fashion, and does not assist maintenance personnel in generating structured inputs, among others. Clearly a need exists for relational databases and structures thereof that are broadly applicable to differing complex systems, such as different aircraft, for assistance with maintenance of the complex systems.
The present invention in varying scope is a relational database for relating maintenance information that differs for each of a plurality of complex systems using a common database structure so as to facilitate maintenance procedures for the plurality of complex systems. One aspect of the invention is a computer based aircraft maintenance and diagnostic system for assistance with fault correction for a fault condition within an aircraft based on a fault model for the aircraft, the system utilizing an inventive embodiment of a relational database.
In one aspect a relational database is defined for relating maintenance information that differs for each of a plurality of complex systems, such as a plurality of different aircraft, using a common database structure so as to facilitate maintenance procedures for the plurality of complex systems. The database structure comprises: a plurality of primary entities for providing a fault model description of each of the plurality of complex systems, the fault model description including, for each of the plurality of complex systems, failure modes, symptoms and data required to effect a repair; and a categorical entity corresponding to a complex system that enables selection of the fault model description corresponding to the complex system. The categorical entity may further include a complex system type and a set of tags that cross reference relevant information within the plurality of primary entities that correspond to the complex system type or a thesaurus entity that facilitates a user""s interface to the relational database by providing a relationship between words used interchangeably in complex system maintenance. This arrangement and common database structure advantageously provides a new fault model description for a new complex system by entering only new information corresponding to the new complex system in the plurality of primary entities and the categorical entity.
In further detail the plurality of primary entities may further include one or more of: an observation entity that includes one of a user reported and automatically reported indication of a problem indexed to an observation code; a fault code entity including a fault code for each distinct set of observation codes that indicate a problem with a system of the complex system; a subsystem entity that includes a subsystem corresponding to one or more fault codes and one of a corresponding list of repairs, list of isolation procedures, and list of deferral procedures, the subsystem entity may be further arranged to consolidate a plurality of fault codes and when each fault code results in the same maintenance procedure indicating that maintenance procedure without resolving a specific fault code; a isolation entity including isolation procedures each having one or more outcomes; or an outcome entity having outcomes with each of the outcomes associated with one isolation procedures and one or more repairs wherein an interactive process of performing isolation procedures with resultant outcomes will resolve the one or more repairs to a specific repair.
In differing scope a relational database is defined for relating maintenance information that differs for each of a plurality of complex systems using a common database structure so as to facilitate maintenance procedures for the plurality of complex systems. Here the database structure comprises: a categorical entity corresponding to a complex system that enables selection of a fault model description corresponding to the complex system; and a plurality of primary entities for providing the fault model description corresponding to the complex system selected according to the categorical entity from a plurality of fault model descriptions of the plurality of complex systems, the plurality of fault model descriptions including, for each of the plurality of complex systems, failure modes, symptoms and data required to effect a repair; wherein the plurality of primary entities facilitate classification of a fault condition and then fault isolation and repair procedures to correct the fault condition. The plurality of primary entities may further include one of a procedure entity and a document reference entity that correlate with known maintenance procedures. The categorical entity may further include a thesaurus entity that facilitates conversion of unstructured user inputs into structured inputs or a change package entity that identifies a set of changes for the complex system and optionally controls when the set of changes becomes active for the complex system.
In another inventive aspect an aircraft maintenance and diagnostic system is defined for assistance with fault correction for a fault condition within an aircraft based on a fault model for the aircraft. The system comprises: a user interface; a computer, coupled to the user interface, having a processor and memory for storing software instructions and a relational database; the processor executing the software instructions to process information to facilitate the identification and correction of the fault condition within the aircraft according to a fault model defined by the relational database where the relational database is defined above.